Woman, 23, questioned over Helensburgh crash that left cyclist with broken back

Police are questioning a 23-year-old woman over a hit-and-run crash south of Sydney that left a cyclist in hospital with a broken back.

Brendan Braid, 58, remains in a stable condition in the intensive care unit of St George Hospital after he was struck by a vehicle on the Old Princes Highway at Helensburgh at 6.15am on Sunday.

The driver of the vehicle did not stop to help Mr Braid, an accountant from the Sutherland area, who was found a short time later lying near his mangled bike with fragments of a car mirror scattered around him. He is believed to have been knocked unconscious.

Police on Monday made a public appeal to find an older model white Ford Laser that was seen driving on the highway about the time of the crash. The vehicle had green P-plates and Victorian registration plates.

A NSW Police spokeswoman said police had located the car following the appeal.

The spokeswoman said the woman was assisting police with their inquiries. No charges have been laid.

Phillip Kelly, also from the club, said he visited Mr Braid in hospital on Monday night, and doctors believed he would regain movement despite his injuries.

"The spinal cord is not damaged so he should [regain movement]," Mr Kelly said.

"His spirits are quite high. He is a very friendly guy. We were joking around."

Mr Kelly said he was riding in the same area on the morning of the crash, and came upon the scene about 30 minutes after it occurred.

"It happened at the top of a hill, it's a dual lane travelling south. There's plenty of room to pass him," he said.

"Unfortunately he [Mr Braid] was riding by himself and no one was with him at the exact time that it happened.

"It's very upsetting and disappointing, just for someone to leave that person curled up by the side of the road. It's unbelievable. For them to just leave a human being wounded like that, they can't be in a reasonable state of mind."

Two cyclists riding up Garrawarra Hill a few minutes after the crash found Mr Braid. They called paramedics and tried to give him first aid.

One cyclist wrote on Facebook: "I got there at the same time as the ambulance and cannot believe that someone could drive off and leave someone in that condition."

The old highway was bypassed by the present Princes Motorway, and is usually quiet and is popular with cyclists on weekends.

On the same day that Mr Braid was hit, another cyclist was struck by a truck in a hit-and-run crash in Kemps Creek in Sydney's west.

Police said the 26-year-old woman, who was wearing a helmet, was riding along Mamre Road about 8.40pm when she was struck from behind.

The woman was knocked unconscious and the driver did not stop to help her, police said.

Witnesses called emergency services to say the woman was suffering from head, neck and shoulder injuries.

Paramedics took her to Liverpool Hospital in a serious condition and she was admitted to the intensive care unit.

Police are appealing for information about either crash to contact Crime Stoppers on 1800 333 000 or visit the Crime Stoppers online reporting page.